Methanol-to-olefin processes are well described in the art. Typically, methanol-to-olefin processes are used to produce predominantly ethylene and propylene. An example of such a methanol-to-olefin process is described in WO-A 2006/020083. In the process of WO-A 2006/020083, the methanol is first converted into dimethylether (DME) prior to be subjected to a conversion to olefins, thereby reducing the amount of water produced during the conversion to olefins. Both methanol and DME are suitable feedstocks for a Methanol-to-olefin process and therefore such processes are also generally referred to as oxygenate-to-olefin (OTO) processes.
In EP2024303A1, another OTO process is described wherein in addition to oxygenates, also C5 olefins are provided to the OTO process. These C5 olefins are provided as an olefinic co-feed together with the oxygenates. By providing a C5 olefinic co-feed to the OTO process more ethylene and propylene may be produced. According to EP2024303A1, suitable sources for these C5 olefins are for instance C5 hydrocarbon fractions obtained from refinery units such as thermal cracking units, catalytic cracking units, steam cracking units, naphtha (steam) cracking units, gasoil (steam) cracking, hydrowax (steam) cracking, isoprene extraction units, semi-hydrogenation units for removal of C5 diolefins, and Fischer-Tropps synthesis units.
However, these C5 hydrocarbon fractions, in particular those obtained from the effluent of a steam cracking units, contain significant amounts of cyclopentene, especially after semi-hydrogenation units. A disadvantage of providing cyclopentenes to an OTO process is that these cyclopentenes react with methanol to form undesired C6 and C7 naphtpenics through an alkylation reaction of the cyclopentene with methanol without producing ethylene and/or propylene.
A further disadvantage of providing cyclopentenes to an OTO process is that these nathphenic C5 hydrocarbons are relatively high boiling and as such are a major blending component in the fuel pool.
By providing the cyclopentene to an OTO process, less C5 hydrocarbons are available for the fuel pool, which may lead to a discrepancy between the fuel demand and supply.
There is a need in the art for a process, which allow the provision of C5 olefins from a C5 hydrocarbon fraction obtained from for instance steam cracking units, while the cyclopentenes remain available for the transportation fuel pool.